Organic farmer Margot McMillen holds a grape leaf damaged by pesticide drift on her farm, Terra Bella Farm, in central Missouri. Kristofor Husted/Harvest Public Media hide caption

itoggle caption Kristofor Husted/Harvest Public Media

Using chemicals to control bugs or mold is common among commercial cannabis growers. But with no federal oversight, experts are concerned growers may be using dangerous pesticides. Ted S. Warren/AP hide caption

itoggle caption Ted S. Warren/AP

Pam Marrone (right), founder and CEO of Marrone Bio Innovations, inspects some colonies of microbes. Marrone has spent most of her professional life prospecting for microbial pesticides and bringing them to market. Dan Charles/NPR hide caption

itoggle caption Dan Charles/NPR

A honeybee forages for nectar and pollen from an oilseed rape flower. Albin Andersson/Nature hide caption

itoggle caption Albin Andersson/Nature

Central Illinois corn farmer Jerry McCulley refills his sprayer with the weedkiller glyphosate on a farm near Auburn, Ill. A new assessment of the chemical finds that the (uncertain) risks mainly affect the people who work with it or who come in direct contact with areas where it's applied. Seth Perlman/AP hide caption

itoggle caption Seth Perlman/AP
Samuel LaHoz/Intelligence Squared U.S.

Corn farmer Jerry McCulley sprays the weedkiller glyphosate across his cornfield in Auburn, Ill., in 2010. An increasing number of weeds have now evolved resistance to the chemical. Seth Perlman/AP hide caption

itoggle caption Seth Perlman/AP

The U.S. Geological Survey found that neonicotinoids are leaching into streams and rivers in the Midwest, including the Missouri River, shown here in Leavenworth, Kan. Dean Bergmann/iStockphoto hide caption

itoggle caption Dean Bergmann/iStockphoto

A Costa Rican banana worker carries a stalk of freshly harvested fruit on a plantation in Costa Rica, where many of the bananas that Americans eat are grown. Kent Gilbert/AP hide caption

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A cornfield is shrouded in mist at sunrise in rural Springfield, Neb. Nati Harnik/AP hide caption

itoggle caption Nati Harnik/AP

Farmworkers harvest and package cantaloupes near Firebaugh, Calif. Gosia Wozniacka/AP hide caption

itoggle caption Gosia Wozniacka/AP

Beekeepers demonstrate at the EU headquarters in Brussels Monday, as lawmakers vote on whether to ban pesticides blamed for killing bees. Georges Gobet/AFP/Getty Images hide caption

itoggle caption Georges Gobet/AFP/Getty Images